Modulation is an integral part of digital communication. Communication systems are incorporated in many portable devices which have limited energy and so the pursuit of increasing the energy efficiency of digital modulation is important. In wireless digital communication, modulation is used to transmit digital data by analog means. To do this, digital symbols are embedded into a carrier wave, passed through a medium or channel, and extracted from the carrier on the receiving side. Symbols can be modulated into a carrier wave by changing the amplitude, frequency, and/or phase of the carrier. In modulation, changes to the amplitude, phase or frequency are called Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), and Frequency Shift Keying (FSK) respectively. Combinations of these exist. One combination in particular is Quadrature Amplitude Modulation (QAM) which combines ASK and PSK. Presently these systems are not wholly satisfactory in the area of power and modulation efficiency. Typically in available systems one can choose to have either efficient modulation but not efficient amplification or efficient amplification but not efficient modulation. To explain: PSK, which is not the most efficient type of modulation can use efficient non-linear amplifiers, e.g. class C amplifiers. QAM can provide very efficient modulation but it must use inefficient linear amplifiers, e.g. class A, class AB.